Suppression of metal catalysis



Patented May 12, 1942 siren STATES- 2,282,936 I SUPPRESSION or METAL CATALYSIS Joseph A. Chenicek, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware No Drawing. Application April 29, 1940,

' Serial No. 332,271

' 6 Claims.

other deleterious oxidation products has been practiced. They are particularly useful in cracked, reformed, and polymer gasolines which. contain relatively high concentrations of monoolefins and somewhat smaller concentrations of other unsaturated hydrocarbons such as diolefins.

The function of inhibitors is primarily to minimize or prevent such oxidation reactions and thus keep the motor fuel in satisfactory condition for use in internal combustion engines. They tend to prevent losses in anti-knock value which accompanies oxidation of this type of gasoline. Among the materials which have been used are Various phenolic and amino compounds as well as fractions of wood tar oil, etc. which are usually added to the gasoline in concentrations of approximately 0.001-0.1%, depending upon the effectiveness of the particular compound used and the gasoline to which it is added. Although inhibitors are used in both treated and untreated gasolines, it is with the latter type that they find the greatest application. Treated gasolines are those which have been subjected to chemical refining processes such as sulfuric acid, fuller's earth and the like, either with or without a sweetening treatment following. Untreated gasolines are those which have received no refinement beyond possibly caustic washing and/or sweetening. The former type of gasoline is usually relatively stable and requires little or no added inhibitor, although the use in inhibitors has been practiced to supplement other refining methods. In the case of untreated gasolines, on theother hand, many of them are unstable and require the protection afforded by inhibitors to prevent undue deterioration during the time they are in storage. I

Practically all gasolines require some form of sweetening treatment in order to improve the odor thereof and produce a product having a negative doctor test. The sodium plumbite or doctor process, as well as the hypochlorite with considerable success. During recent years, theso-called copper sweetening process has been developed in which gasoline is contacted with .a copper-containing reagent. As a result of the presence of relatively minor amounts of impurities in such gasolines, the sweetened gasoline usually contains relativelysmall amounts of copper compounds which have a catalytic efiect on oxidation reactions which may result when the gasoline comes in contact with air. Various methods have been developed for removing such copper compounds including treatment with alkali or alkaline earth metal sulfides and heavy metal sulfides such as zinc sulfide and the like.

In some instances, however, these reagents may not be completely effective in removing the copper from the gasoline and as a consequence the gasoline may have a reduced stability and susceptibility to added gasoline gum inhibitors. Moreover gasolines come in contact with various metals in the course of refining, storing and shipping operations, and this may result in the gasoline containing minute amounts of such metals as copper, iron, cobalt, nickel and the like which are oxidation catalysts.- It is with a method of preventing depreciation due to the presence of such catalysts that this invention is concerned.

In one specific embodiment the present invention comprises a method for suppressing the catalytic action of heavy metal compounds which may be contained in hydrocarbon distillates such as cracked gasolines and which tend to promote the formation of gum therein, by adding to said gasoline approximately 0.0001-0.01% of a condensation product of an orthohydroxy naphthaldehyde with an aminophenol, either with or without a gasoline gum inhibitor.

Compounds of this type may be represented by the general formula:

A typical example is 2-hydroxy-l-naphthylidene orthoaminophenol.

The compounds of this invention, which are hereinafter termed suppressers, are not necessweetening process, have been used in the past sarlly exactly equivalent. Furthermore they posgsacas In some cases the compounds may be used in the gasoline without added gum inhibitors. This is particularly true when used in connection with straight-run distillates or cracked gasolines which have been refined to an adequate degree.

of stability such as by acid-treatment or other suitable methods. However these compounds are not of themselves gasoline gum inhibitors except to a minor extent, so that they do not result in a gasoline of improved stability except when metal compounds are present therein.

However, the usual method of application is to add both the suppresser and the gasoline gum inhibitor simultaneously. The resulting induction period is usually the same or slightly increased .over that obtainable with the inhibitor alone in a gasoline free of metal compounds. The suppresser may be dissolved in the gasoline gum inhibitor. As a rule, smaller, amounts of the suppresser are required than of the gum inhibitor so that a relatively minor amount of the suppress er may be added to the inhibitor, say for example, less than 50% of the total mixture. When using inhibitors of theaminophenol type, the orthohydroxy-naphthaldehyde in alcoholic solution can be added directly to the inhibitor.

The following example is given to illustrate the usefulness of the invention, but should not be tion period when the copper was completely removed was approximately 100 minutes and with the copper present was approximately 40 minutes. By adding 0.001% of 2-hydroxy-l-naph- 'aa'a'aeae thylidine-ortho-aminophenol, the induction period was increased in minutes. When adding 0.01% of a commercial gum inhibitor to the copper-containing gasoline without a suppresser present, the induction period was minutes. When u'singthe 0.01% of the inhibitor together with 0.001% of the suppresser, the induction period was'495 minutes. This compared. with-an induction periodfof 325 minutes for a copper-freetively small amount of 2-hydroxy-1-naphthyli-' dene-ortho-aminophenol.

3. Motor fuel comprising olefinic gasoline containing a relatively small amount of-a -hydroxynaphthaldehyde in which the oxygen atom of the aldehyde group has been replaced-by an aminophenol group.

4. Motor fuel comprising olefinic gasoline containing a relatively small amount of 2-hydroxyl-naphthylidene-ortho-aminophenol.

5. Motor fuelcomprising olefinic gasoline containing a gum inhibitor and a relatively small amount of a hydroxy-naphthaldehyde in which the oxygen atom of the aldehyde group has been replaced by an aminophenol group.

6. Motor fuel comprising olefinic gasoline containing a gum inhibitor and a relatively small amount of 2-hydroxy-l-naphthylidene-orthoaminophenol.

JOSEPH A. CHENICEK. 

